A laminate having metal layers laminated on a transparent substrate such as glass (hereinafter referred to as “metal-containing laminate”) is widely used for e.g. window glass of buildings and automobiles with a purpose of e.g. suppressing emission of heat ray to decrease a load on air conditioning. Further, the metal-containing laminate is used also as a shielding material to suppress leakage of electromagnetic wave radiating from an apparatus such as a plasma display.
In a case where the metal-containing laminate is applied to e.g. window glass, a high visible light transmittance is required together with a small emission of heat ray, and at the same time, a low visible light reflectance and a preferred reflection color tone are required.
Further, in a case where the metal-containing laminate is used as an electromagnetic wave shielding material, together with a high electrical conductivity, a visible light transmittance as high as possible and a visible light reflectance as low as possible, and further, a preferred reflection color tone are required.
With respect to the metal-containing laminate, it is required that the wavelength range showing a low reflectance is broad in the visible light region in order to obtain a low visible light reflectance and a preferred reflection color tone.
Further, it is well known that a laminate having a layer constitution wherein dielectric material layers and metal layers are alternately laminated one on another is suitable to obtain a high visible light transmittance together with a low emissivity and an electrical conductivity.
A low heat ray emissivity (i.e. a high electrical conductivity) alone can be obtained by making the metal layer thick. However, it may cause decrease in the visible light transmittance and increase in the visible light reflectance. Further, the wavelength range in which a low reflectance can be obtained in the visible light region tends to be narrow, whereby a preferred reflection color tone may be impaired.
It is generally known that a phenomenon caused by making the metal layer thick (the above unfavorable phenomenon that the reflection color tone is impaired) can be diminished in a case where a material having a high refractive index such as titanium oxide is used as the dielectric material layer, as compared with a case where a material having a refractive index lower than that of titanium oxide is used.
Further, it is generally known that the phenomenon caused by making the metal layer thick can be diminished also in a case where the number of lamination is increased.
Actually, when a laminate is constituted by using titanium oxide layers as the dielectric material layers, the wavelength width in which a low reflectance can be obtained in the visible light region can be broadened as compared with a case of using a material having a refractive index lower than that of titanium oxide, whereby a more preferred reflection color tone can be obtained. However, there is such a problem that the visible light transmittance tends to decrease, and further, the rate of decrease in the visible light transmittance tends to increase together with the increase in the number of lamination.
Further, there is such a problem that a laminate constituted by using titanium oxide layers as the dielectric material layers has a low abrasion resistance.
It is an object of the present invention to improve the transmittance in the visible light region with respect to a laminate employing a titanium oxide.
Further, it is an object of the present invention to improve abrasion resistance with respect to a laminate employing a titanium oxide.